The OSI Model (Open Systems Interconnection Model) The OSI model (Open System Interconnection Model) is a conceptual framework that used to describe seven layers that computer systems use to communicate over a network. It was the first standard model for network communications, adopted by all major computer and telecommunication companies in the early 1980s. The OSI was published in 1984 by the International Organization for Standardization (ISO). The OSI model characterizes computing functions into a universal set of rules and requirements in order to support interoperability between different products and software. In the OSI reference model, the communications between a computing system are split into seven different abstraction layers as shown picture above: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Though it does not always map directly to specific systems, the OSI Model is still used today as a means to describe Network Architec